The present invention relates to an adjusting mechanism for an adjustable chair, the frame of which has an adjustable seat carrier and/or an adjustable back rest carrier. Both carriers are supported on a pedestal and together with the latter form the chair frame. A spring mechanism is provided, one end of which is supported on the pedestal and the other end of which is supported on the seat carrier or the backrest carrier and which can be locked and unlocked by a control device.
Chairs with the frame having an adjustable seat carrier and/or an adjustable back rest carrier are known in numerous different designs. The movable part of the chair frame, independently on whether it is in the form of the back rest carrier, the seat carrier or both carriers, must be supported on the pedestal with a spring mechanism, so that it is possible to counteract the force exerted by the chair user. This spring mechanism is e.g. a gas spring or a helical spring.
For increasing sitting comfort, it is known to block the spring mechanism in a particular position of the chair frame and consequently fix the chair position. For this purpose, the chair frame carries an operating mechanism, with which it is possible to block the spring mechanism and therefore the chair frame. The operating mechanism requires two different adjusting levers, namely a first adjusting lever for blocking the spring mechanism and a further adjusting lever for releasing the blocked spring mechanism. This solution is not simple and is not advantageous for the user.